What should be considered in the design of pressure vessels when the medium contains hydrogen sulfide, CO2, water, and CL-?

Hydrogen sulfide poses a moderate level of hazard; in addition, there is intergranular corrosion caused by hydrogen sulfide, and stainless steel materials cannot be used in the presence of chloride ions. Hehe. That’s all I know.

It is recommended to refer to the \"Handbook on Corrosion and Protection of Equipment in Petrochemical Plants\"

If it is made of stainless steel, the chloride ion content should be less than 25 ppm. In the case of CS material, stress corrosion may occur under the influence of hydrogen sulfide; therefore, CS steel plates also need to be ultrasonically inspected one by one

It’s not clear whether it refers to the presence of these components in the medium or a single case. If mixed, the situation becomes more complex; any of them can cause corrosion, and this is related to factors such as concentration and temperature. If it’s a single case, it’s simple enough to just consider each situation individually.

The main thing to pay attention to is the material selection; this issue involves a wide range of aspects. It is recommended to consult the book on steels for steel pressure vessels in the comprehensive handbook on chemical equipment design. As for the second floor, it should be noted that the presence of CL does not mean that stainless steel cannot be used; however, the stainless steel used in such cases is not ordinary stainless steel. But regarding the equipment mentioned by the original poster, it is not recommended to use stainless steel – there are too many factors to consider

Stress corrosion, the corrosive effect of Cl ions on austenitic stainless steels

The main thing to pay attention to is corrosion issues: 1. Stress corrosion – stress corrosion cracking can occur in aqueous solutions containing hydrogen sulfide and CL-, so it should be avoided at all costs. Environments that cause stress corrosion in carbon steel, low-alloy steel, austenitic stainless steel, and ferritic chromium stainless steel. 2. Intergranular corrosion: In CL- containing aqueous solutions, CL- easily combines with chromium in austenitic stainless steel, resulting in a chromium-deficient condition at the grain boundaries and thus causing intergranular corrosion. 3. Hydrogen damage: In an environment of hydrogen sulfide and water, free hydrogen may penetrate into the metal, leading to a deterioration in its mechanical properties. Pay attention to the proper use of corrosion-resistant materials, such as chromium-nickel stainless steels with high silicon content, ferritic stainless steels, high-nickel stainless steel alloys, and non-ferrous metals, etc ； Targeted anti-corrosion materials can also be used, such as asphalt-based anti-corrosion coatings, zinc-rich anti-corrosion coatings, and rubber linings.

It mainly relates to material selection, and whether heat treatment is applied after manufacturing, among other issues

It is mainly a problem with the corrosion resistance of the container. Hydrogen sulfide, CL-, and CO2 all exhibit certain corrosive properties when dissolved in water. If the chloride ion concentration is very high, stainless steel 316L can be chosen as the material for the container. However, the technical requirements in the design drawings should state that the inner surface of the tank must be pickled and passivated. Prevent corrosion at the welded joints of the container.

Use 0Cr13 and 0Cr13Al

Of course, for hydrogen sulfide stress corrosion, it is essential to determine whether the conditions for such corrosion are met; if so, material selection must be carried out in accordance with the HG20580~20585-1998 standards, along with corresponding manufacturing inspection requirements. As for CL ions, they pose a significant problem, and material selection becomes quite challenging in such cases – the specific choices depend on temperature and pressure. It’s best to check the relevant material selection standards.

I only know that for carbon steel and low-alloy steel plates with a thickness of 12 mm or more, ultrasonic testing must be performed on each sheet in a wet H2S corrosion environment.